This invention relates generally to closure cap constructions of the type that are intended to be assembled onto the necks of existing containers, and which employ a base part that is captive on the container, and a sealing cap or overcap connected to the base part by means of an integral hinge structure.
Various closure devices of the type noted above have been proposed and produced in recent years. Typical arrangements are disclosed in U.S. Pat. Nos. 3,124,281; 3,877,598; and 4,377,248. All of the patented devices involve a base part that is either screwed onto a container neck, or otherwise secured thereto, as by a snap fit. An integral hinge structure was generally employed for holding captive the overcap and preventing it from inadvertently becoming misplaced, etc. during use of the dispenser. The length of the hinge was sufficient to allow the overcap to be readily swung between its closed or sealing position and its open or discharging position.
In automated assembly where automatic capping equipment is employed, the closure cap devices were held in suitable fixtures, and torque was applied to the base part in order to screw it onto the particular container neck. When this was done, there was virtually no stress or force applied to the overcap, and thus no tendency for there to occur breakage or stretching of the hinge. However, recently it has been necessary for certain applications, to employ existing capping equipment that was not capable of applying torque to the base part. In constructions such as those illustrated in the above patents, if the amount of torque was sufficiently great, the overcap slipped with respect to the base part, and caused either stretching or breakage of the hinge. The problem would be more serious with arrangements where the hinge was extremely short, as in the case of a "living" hinge, that is, one which was constituted for the most part as a membrane in the form of a fold along a line of weakness between two more rigid parts. Typical constructions are shown in U.S. Pat. Nos. 4,377,247; 4,220,248; 3,240,405; and 4,261,486.
It appears that the problem of potential breakage of a hinge in a cap construction is not addressed in any of the above patents.
Another area which caused concern was a tendency for product to build up around the area outside of a spout or discharge opening in a dispenser. When this occurred, the material usually dried out and hardened. Where the product being dispensed was a glue or adhesive, the hardened product eventually built up to an extent where it interfered with proper opening and closing of the cap. With other substances, such as foods, the hardened product had to be removed, and the cap cleaned periodically. The problem was especially troublesome where the discharge orifice took the form of an upstanding spout, that is, one which projected a substantial distance around an upper or top wall of a base cap. Several of the above patents show devices possessing this characteristic spout; the problems with dried product accumulating around the outside of the spout can be readily appreciated.